Finding the Fourth Proportional to 1,288.69, 1,931.70 and 979.90

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.69 : 1,931.70 = 979.90 : x
2. Step 2: Convert to fraction form
   1,288.69/1,931.70 = 979.90/x
3. Step 3: Cross multiply
   1,288.69x = 1,931.70 × 979.90
4. Step 4: Simplify right side
   1,288.69x = 1,892,872.83
5. Step 5: Solve for x
   x = 1,892,872.83/1,288.69
6. Step 6: Final answer
   x = 1,468.83